Slide rule



June 17, 1947. H. M. KALVJFMAN SLIDE RULE Filed June 14, 1946 w mm mn S/ Q mw IG fw m N@ Y L ....IxllllNUUnulxdl...nHUHHLIHMHHIIMHHIIHMUHHduHNMHNHalli-HNHHNJHHnvdHlllnhlJdHummU/ WQ N\\ M. W\ \Q\ ------------.--5:yEEEN -SEQQQ N S322m@nww. w -iure@mimig---,-- -T--- S ,mw mvv LIN RNEY Patented June 17, 1947 UNITED STATES PATENT OFFICE SLIDE RULE Hyman M. Kaufman, Amesbury, Mass.

Application June 14, 1946, Serial No. 676,796

(Cl. 23S-70) 2 Claims. 1

This invention relates to a slide rule for teaching children addition and subtraction and h'as for an object to provide a novel and improved device of the above type.

Another object is to provide a device of the above type in which the numbers to be added or subtracted always appear one beneath the other as in the usual addition and substraction problems.

Another object is to provide a device of the above type which is easy for a child to understand and manipulate.

Another object is to provide a slide rule of the above type in which the answer always appears at the same designated position whether adding or subtracting.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are characteristic of this invention are pointed out more particularly in the claims, the invention will be better understood by referring to the following description, taken in connection with the accompanying drawing in which a specic embodiment has been set forth for purpose of illustration.

In the drawing:

Fig. 1 is a plan view of a slide rule embodying my invention;

Fig. 2 is a side elevation thereof; and

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 1.

Referring to the drawings kmore in detail the device is shown as comprising a base I having a channel formed therein containing a slide I I. The base ID and slide II are provided with cooperating grooves I2 and tongues I3 respectively which guide the slide II.

In the embodiment shown the base carries a pair of scales I5 and I6 and the slide II carries a scale I1 which registers therewith. Each scale is divided into a set of equal spaces. The spaces of the scale I5 carry numbers in arithmetical progression from 0 to 9, reading from the left to right. The spaces of the scale I5 carry numbers in arithmetical regression from 9 to 0, reading from left to right. The spaces of the scale I6 are displaced one space to the right from the spaces of the scale I5 so that l on the scale I5 appears over the 9 on the scale I6 and vice versa.

The scale I1 is divided into I9 spaces carrying numbers in a double arithmetical regression each extending from 9 to 1 and having a zero interposed between the central 1 and 9.' In order to distinguish the two regressions of the scale I1 the left hand regression from 9 to 0 is shown as italicized or slanting wh'ereas the numbers of the right hand regression 9 to I are straight. The numbers may be distinguished in other ways if desired as by being of different colors. An answer arrow i8 is positioned on the scale I1 above the 0 to point to a number on the scale I5 which becomes the answer as will be described.

For addition the two numbers to be added are placed one beneath the other by manipulation of the slide and the answer appears above the arrow I3. As shown in Fig. 1 "5 on scale I1 appears below "1 on scale I5 and the answer 6 appears above the arrow I8. Likewise other number combinations which add up to 6 appear one above the other, as 2 and "4, "3 and 3, etc. When a slant number on the scale I1 is added to a number on the scale I5 the answer appears as indicated. When a straight number on the scale l1 is added to a number on the scale I 5 the answer number must be mentally increased by ten, as "7 and 9 equal 16. This gives the child practice in carrying the digit as in usual addition problems.

For subtraction the minuend on the scale I1 is brought directly above the subtrahend on the scale I6 by manipulation of the slide II and the answer will appear above the arrow I8 as before. In the position shown in Fig. 1 the number 1 on the scale I6 appears below the number "7 on the scale I1. The answer 6 appears above th'e arrow I8. Likewise other combinations which subtract to 6 appear on the scales I 1 and I6, as 9 and 3, 8 and 2, etc. When the minuend is a slant number on the scale I1 it is considered as increased by ten as 8 on scale I6 from 14 on scale I1. In this case also the child is taught the mental borrowing step required in practical subtraction problems.

Obviously all of the numbers on the various scales may be reversed in order, or the numbers on the slide may be reversed in which case the arrow I8 will point to the scale I6. In either case the operation will be the same.

Preferably the numbers on the slide are given a distinctive color, such as red, to distinguish them from the black numbers on the iixed scales. The use of a different color for the numbers oi' the slide makes the rule simpler for a child to understand than if three numbers all the same color occurred one under the other. The separate color on the slide makes the grouping of two numbers constituting the addends, or two numbers constituting the minuend and subtrahend, easier for the mind to picture and retain.

It will be evident that the child may be drilled with the various addition and subtraction problems as required and the appearance of the numbers to be added or subtracted one above the other gives the child a mental picture of the problem as he will normally encounter the sarne.

Although a specic embodiment has been shown for purposes of illustration, it is to be understood that variations may be made there in and the invention may be applied to other uses as will readily appear to a person skilled in the art. The invention is only to be limited in accordance with the scope of the following claims.

What is claimed is:

l. A slide rule for addition 4and subtraction comprising a base member and a .slide carried thereby, a pair of scales on said base above and below said slide respectively and a scale on said slide to cooperate therewith, said scales being divided rinto equal spaces, the spaces of the one o said base scales carrying numbers in arith met-ical progression from 0 to 9, the spaces of the other of said base scales carrying numbers in .arithmetical regression "from 9 to 0 with the 9 on each of said scales registering with the i on the other scale, the spaces of said slide scale carrying numbers in a double arithmetical regression from 9 to 0 and 9 to l and an index mark on said :slide registering with the 0 thereon vand with the first mentioned base scale.

2. A slide rule for Vaddition and subtraction comprising a base member and a slide carried thereby, a pair of scales on said base above and below said slide respectively and a scale on said slide to cooperate therewith, said scales being divided into equal spaces, the spaces of the one of said base scales carrying numbers in arithmetical progression from 0 to 9, the spaces of the other of said base scales carrying numbers in arithmetical regression from 9 to 0" with the 9 on each of said scales registering with the l on the other scale, the spaces of said slide scale carrying numbers in a double arithmetical series, each series extending from l to 9, with a 0 interposed between said series, and an index mark on said slide registering with the "0 thereon and with the base scale in which the numbers progress in a direction opposed tc the numbers on said slide.

HYMAN M. KAUFMAN.

Country Date England 1904 OTHER REFERENCES Pages 22, 23, 24, and 25 of Arnolds Special Slide Rules, in September 1933, published by Purdue University. (Copy in Div. 41 of Patent Office.)

Number 

